/*	$Id: kern_clock.c,v 1.1.1.1 2006/09/14 01:59:08 root Exp $ */
/*	$OpenBSD: kern_clock.c,v 1.21 1999/08/15 00:07:43 pjanzen Exp $	*/
/*	$NetBSD: kern_clock.c,v 1.34 1996/06/09 04:51:03 briggs Exp $	*/

/*-
 * Copyright (c) 1982, 1986, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)kern_clock.c	8.5 (Berkeley) 1/21/94
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/callout.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <vm/vm.h>

#include <machine/cpu.h>

extern void    psignal __P((struct proc *p, int sig));

/*
 * Clock handling routines.
 *
 * This code is written to operate with two timers that run independently of
 * each other.  The main clock, running hz times per second, is used to keep
 * track of real time.  The second timer handles kernel and user profiling,
 * and does resource use estimation.  If the second timer is programmable,
 * it is randomized to avoid aliasing between the two clocks.  For example,
 * the randomization prevents an adversary from always giving up the cpu
 * just before its quantum expires.  Otherwise, it would never accumulate
 * cpu ticks.  The mean frequency of the second timer is stathz.
 *
 * If no second timer exists, stathz will be zero; in this case we drive
 * profiling and statistics off the main clock.  This WILL NOT be accurate;
 * do not do it unless absolutely necessary.
 *
 * The statistics clock may (or may not) be run at a higher rate while
 * profiling.  This profile clock runs at profhz.  We require that profhz
 * be an integral multiple of stathz.
 *
 * If the statistics clock is running fast, it must be divided by the ratio
 * profhz/stathz for statistics.  (For profiling, every tick counts.)
 */

/*
 * TODO:
 *	allocate more timeout table slots when table overflows.
 */


/*
 * Bump a timeval by a small number of usec's.
 */
#define BUMPTIME(t, usec) { \
	register volatile struct timeval *tp = (t); \
	register long us; \
 \
	tp->tv_usec = us = tp->tv_usec + (usec); \
	if (us >= 1000000) { \
		tp->tv_usec = us - 1000000; \
		tp->tv_sec++; \
	} \
}

int	stathz;
int	schedhz;
int	profhz;
int	profprocs;
int	ticks;
static int psdiv, pscnt;		/* prof => stat divider */
int	psratio;			/* ratio: prof / stat */
int	tickfix, tickfixinterval;	/* used if tick not really integral */
static int tickfixcnt;			/* accumulated fractional error */


volatile struct	timeval time;
volatile time_t time_uptime;
volatile struct timeval mono_time;

/*
 * Initialize clock frequencies and start both clocks running.
 */
void
initclocks()
{
	register int i;

	/*
	 * Set divisors to 1 (normal case) and let the machine-specific
	 * code do its bit.
	 */
	psdiv = pscnt = 1;
	cpu_initclocks();

	/*
	 * Compute profhz/stathz, and fix profhz if needed.
	 */
	i = stathz ? stathz : hz;
	if (profhz == 0)
		profhz = i;
	psratio = profhz / i;

}

/*
 * The real-time timer, interrupting hz times per second.
 */
void
hardclock(frame)
	register struct clockframe *frame;
{
	register struct callout *p1;
	register struct proc *p;
	register int delta, needsoft;
#ifdef NOTUSED_BY_PMON
	extern int tickdelta;
	extern long timedelta;
#endif /* NOTUSED_BY_PMON */

	/*
	 * Update real-time timeout queue.
	 * At front of queue are some number of events which are ``due''.
	 * The time to these is <= 0 and if negative represents the
	 * number of ticks which have passed since it was supposed to happen.
	 * The rest of the q elements (times > 0) are events yet to happen,
	 * where the time for each is given as a delta from the previous.
	 * Decrementing just the first of these serves to decrement the time
	 * to all events.
	 */
	needsoft = 0;
	for (p1 = calltodo.c_next; p1 != NULL; p1 = p1->c_next) {
		if (--p1->c_time > 0)
			break;
		needsoft = 1;
		if (p1->c_time == 0)
			break;
	}

	p = curproc;
	if (p) {
		register struct pstats *pstats;

		/*
		 * Run current process's virtual and profile time, as needed.
		 */
		pstats = p->p_stats;
		if (CLKF_USERMODE(frame) &&
		    timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
		    itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
			psignal(p, SIGVTALRM);
		if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
		    itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
			psignal(p, SIGPROF);
	}

#ifdef NOTUSED_BY_PMON
	/*
	 * If no separate statistics clock is available, run it from here.
	 */
	if (stathz == 0)
		statclock(frame);
#endif /* NOTUSED_BY_PMON */

	/*
	 * Increment the time-of-day.  The increment is normally just
	 * ``tick''.  If the machine is one which has a clock frequency
	 * such that ``hz'' would not divide the second evenly into
	 * milliseconds, a periodic adjustment must be applied.  Finally,
	 * if we are still adjusting the time (see adjtime()),
	 * ``tickdelta'' may also be added in.
	 */
	ticks++;
	delta = tick;

	if (tickfix) {
		tickfixcnt += tickfix;
		if (tickfixcnt >= tickfixinterval) {
			delta++;
			tickfixcnt -= tickfixinterval;
		}
	}

#ifdef NOTUSED_BY_PMON
	/* Imprecise 4bsd adjtime() handling */
	if (timedelta != 0) {
		delta += tickdelta;
		timedelta -= tickdelta;
	}
#endif /* NOTUSED_BY_PMON */

#ifdef notyet
	microset();
#endif

	BUMPTIME(&time, delta);
	BUMPTIME(&mono_time, delta);
	time_uptime = mono_time.tv_sec;

	/*
	 * Process callouts at a very low cpu priority, so we don't keep the
	 * relatively high clock interrupt priority any longer than necessary.
	 */
	if (needsoft) {
#ifndef PMON
		if (CLKF_BASEPRI(frame)) {
			/*
			 * Save the overhead of a software interrupt;
			 * it will happen as soon as we return, so do it now.
			 */
			(void)splsoftclock();
			softclock();
		} else
#endif
			setsoftclock();
	}
}

/*
 * Software (low priority) clock interrupt.
 * Run periodic events from timeout queue.
 */
/*ARGSUSED*/
void
softclock()
{
	register struct callout *c;
	register void *arg;
	register void (*func) __P((void *));
	register int s;

	s = splhigh();
	while ((c = calltodo.c_next) != NULL && c->c_time <= 0) {
		func = c->c_func;
		arg = c->c_arg;
		calltodo.c_next = c->c_next;
		c->c_next = callfree;
		callfree = c;
		splx(s);
		(*func)(arg);
		(void) splhigh();
	}
	splx(s);
}

/*
 * timeout --
 *	Execute a function after a specified length of time.
 *
 * untimeout --
 *	Cancel previous timeout function call.
 *
 *	See AT&T BCI Driver Reference Manual for specification.  This
 *	implementation differs from that one in that no identification
 *	value is returned from timeout, rather, the original arguments
 *	to timeout are used to identify entries for untimeout.
 */
void
timeout(ftn, arg, ticks)
	void (*ftn) __P((void *));
	void *arg;
	register int ticks;
{
	register struct callout *new, *p, *t;
	register int s;

	if (ticks <= 0)
		ticks = 1;

	/* Lock out the clock. */
	s = splhigh();

	/* Fill in the next free callout structure. */
	if (callfree == NULL)
		panic("timeout table full");
	new = callfree;
	callfree = new->c_next;
	new->c_arg = arg;
	new->c_func = ftn;

	/*
	 * The time for each event is stored as a difference from the time
	 * of the previous event on the queue.  Walk the queue, correcting
	 * the ticks argument for queue entries passed.  Correct the ticks
	 * value for the queue entry immediately after the insertion point
	 * as well.  Watch out for negative c_time values; these represent
	 * overdue events.
	 */
	for (p = &calltodo;
	    (t = p->c_next) != NULL && ticks > t->c_time; p = t)
		if (t->c_time > 0)
			ticks -= t->c_time;
	new->c_time = ticks;
	if (t != NULL)
		t->c_time -= ticks;

	/* Insert the new entry into the queue. */
	p->c_next = new;
	new->c_next = t;
	splx(s);
}

void
untimeout(ftn, arg)
	void (*ftn) __P((void *));
	void *arg;
{
	register struct callout *p, *t;
	register int s;

	s = splhigh();
	for (p = &calltodo; (t = p->c_next) != NULL; p = t)
		if (t->c_func == ftn && t->c_arg == arg) {
			/* Increment next entry's tick count. */
			if (t->c_next && t->c_time > 0)
				t->c_next->c_time += t->c_time;

			/* Move entry from callout queue to callfree queue. */
			p->c_next = t->c_next;
			t->c_next = callfree;
			callfree = t;
			break;
		}
	splx(s);
}

/*
 * Compute number of hz until specified time.  Used to
 * compute third argument to timeout() from an absolute time.
 */
int
hzto(tv)
	struct timeval *tv;
{
	register long ticks, sec;
	int s;

	/*
	 * If number of microseconds will fit in 32 bit arithmetic,
	 * then compute number of microseconds to time and scale to
	 * ticks.  Otherwise just compute number of hz in time, rounding
	 * times greater than representible to maximum value.  (We must
	 * compute in microseconds, because hz can be greater than 1000,
	 * and thus tick can be less than one millisecond).
	 *
	 * Delta times less than 14 hours can be computed ``exactly''.
	 * (Note that if hz would yeild a non-integral number of us per
	 * tick, i.e. tickfix is nonzero, timouts can be a tick longer
	 * than they should be.)  Maximum value for any timeout in 10ms
	 * ticks is 250 days.
	 */
	s = splhigh();
	sec = tv->tv_sec - time.tv_sec;
	if (sec <= 0x7fffffff / 1000000 - 1)
		ticks = ((tv->tv_sec - time.tv_sec) * 1000000 +
			(tv->tv_usec - time.tv_usec)) / tick;
	else if (sec <= 0x7fffffff / hz)
		ticks = sec * hz;
	else
		ticks = 0x7fffffff;
	splx(s);
	return (ticks);
}

void
microuptime(struct timeval *tvp)
{
	struct timeval tv;

	microtime(&tv);
	timersub(&tv, &boottime, tvp);
}
